In or about the year 1839, Jacobi sailed an electric boat on the Neva, with the help of an electromagnetic engine of one horse-power, fed by the current from a battery of Grove cells, and in 1882 a screw launch, carrying several passengers, and propelled by an electric motor of three horse-power, worked by forty-five accumulators, was tried on the Thames.  Being silent and smokeless in its action, the electric boat soon came into favour, and there is now quite a flotilla on the river, with power stations for charging the accumulators at various points along the banks.

Figure 79 illustrates the interior of a handsome electric launch, the Lady Cooper, built for the “E P S,” or Electric Power Storage Company.  An electric motor in the after part of the hull is coupled directly to the shaft of the screw propeller, and fed by “E P S” accumulators in teak boxes lodged under the deck amidships.  The screw is controlled by a switch, and the rudder by an ordinary helm.  The cabin is seven feet long, and lighted by electric lamps.  Alarm signals are given by an electric gong, and a search-light can be brought into operation whenever it is desirable.  The speed attained by the Lady Cooper is from ten to fifteen knots.

M. Goubet, a Frenchman, has constructed a submarine boat for discharging torpedoes and exploring the sea bottom, which is propelled by a screw and an electric motor fed by accumulators.  It can travel entirely under water, below the agitation of the waves, where sea-sickness is impossible, and the inventor hopes that vessels of the kind will yet carry passengers across the Channel.

The screw propeller of the Edison and Sim’s torpedo is also driven by an electric motor.  In this case the current is conveyed from the ship or fort which discharges the torpedo by an insulated conductor running off a reel carried by the torpedo, the “earth” or return half of the circuit being the sea-water.

All sorts of machinery are now worked by the electric motor—­for instance, cranes, elevators, capstans, rivetters, lathes, pumps, chaff-cutters, and saws.  Of domestic appliances, figure 80 shows an air propeller or ventilation fan, where F is a screw-like fan attached to the spindle of the motor M, and revolving with its armature.  Figure 81 represents a Trouve motor working a sewing-machine, where N is the motor which gears with P the driving axle of the machine.  Figure 82 represents a fine drill actuated by a Griscom motor.  The motor M is suspended from a bracket A B C by the tackle D E, and transmits the rotation of its armature by a flexible shaft S T to the terminal drill O, which can be applied at any point, and is useful in boring teeth.